The overall goal of the research programs is to detail the geometry of complexes of polycyclic hydrocarbons bound to DNA and to elucidate the intermolecular interactions which stabilize these complexes, using the newly developed techniques of optically detected magnetic resonance. Our experiments focus on complexes with polycyclic hydrocarbons which have been postulated to be actively involved in carcinogenic activity and which may be of importance in elaborating mechanisms of chemical carcinogenesis at the molecular level.